Check the volume sliders in CUE and see whether you can hear the microphone via sidetone volume as well as pressing the mic mute button on the headset as well.

If that does not help, Try the headset on another computer and see whether the microphone works. If it still does not work, contact your retailer for a replacement or request an RMA via Corsair.https://support.corsair.com/

So I am having the same issue, I spot with support and they mentioned trying on another computer... success!!!

Unfortunately I need it to work on my desktop... so obviously some sort of software isn't playing nicely with the headset it seems.. (just for reference I'm running realtek, NVidia, steam, discord, origin, just to name the key software)